Title:
AFOCAL VARIABLE POWER OPTICAL SYSTEM
Document Type and Number:
Japanese Patent JPH04204614
Kind Code:
A
Abstract:
PURPOSE:To suppress the ratio of a change in the focal length of a diopter adjusting lens group of variable magnifications to a lower level and to lessen the deviation in the diopter at the time of variable power by including a part of the plural variable power lens groups to be moved for the purpose of the variable power into the diopter adjusting lens group to be moved for the purpose of diopter adjustment and excluding the rest from the diopter adjusting lens group. CONSTITUTION:An objective optical system positioned on an object side with a visual field ring S as a boundary is constituted of the fixed 1st lens group G1 and the 2nd lens group G2 to be moved for the purpose of the variable power. An eyepiece optical system to be positioned nearer the eye side than the visual field ring S is constituted of the 3rd lens group G3 to be moved for the purpose of the variable power and the fixed 4th lens group G4. The diopter adjustment is executed by integrally moving the two lens groups 2 enclosed by the broken lines of the 3rd lens group G3 and the 4th lens group G4. Namely, the 3rd lens group G3 is the variable power lens group and is included din the diopter adjusting lens group as well and the 2nd lens group G2 is the variable power lens group but is excluded from the diopter adjusting lens group. The diopter lens is made smaller as compared with the case all of the variable power lenses are included in the diopter adjusting lens group.
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Inventors:
KATO HIROYUKI
OGAWA RYOTA
OGAWA RYOTA
Application Number:
JP33593590A
Publication Date:
July 27, 1992
Filing Date:
November 30, 1990
Export Citation:
Assignee:
ASAHI OPTICAL CO LTD
International Classes:
G02B15/14; G02B15/167; G02B15/173; G02B25/00; (IPC1-7): G02B15/14; G02B15/167; G02B25/00
Attorney, Agent or Firm:
Tamio Nishiwaki